Delivery catheters are often used to position medical devices, for example, one or more medical electrodes, at implant sites within a body of a patient, via minimally invasive techniques. These catheters are constructed having a lumen, which provides a pathway to the implant site, through which an implanting physician may pass the medical device without encountering anatomical obstructions. Some delivery catheters include mechanisms, such as pull-wire actuation, which allow the implanting physician to actively change a curvature of the catheter in order to direct a distal tip of the catheter to a target implant site; while other delivery catheters have pre-formed curvatures tailored to position a distal tip thereof at a particular anatomical site from a particular percutaneous access site, thus eliminating the need to actively control the curvature during the implant procedure.
In certain instances, a patient suffering from bradycardia, tachyarrhythmia and/or heart failure will benefit from electrical stimulation pacing and/or defibrillation electrodes implanted on an epicardial surface of the patient's heart. Minimally invasive methods for accessing the epicardial surface have been developed; these methods may be used by way of a mini-thoracotomy, or in conjunction with a trocar, a cannula or a needle that has been passed, via a percutaneous incision, through an interstitial space between the patient's ribs, or via a percutaneous puncture, or stick at a sub-xiphoid location.
U.S. Pat. No. 4,991,578 describes a method for gaining access to an epicardial surface of a heart, wherein a percutaneous needle is inserted at a sub-xiphoid location until the tip of the needle pierces through a pericardial sac surrounding the heart; a guide wire is then inserted, through a lumen of the needle, into the pericardial space over the epicardium, and the needle is removed. An introducer sheath or a delivery catheter may be inserted over the guide wire into the pericardial space to provide access to the epicardial surface of the heart.
Once access to the epicardial surface is established, for example, by means of tools provided in a pericardiocentesis kit, the implanting physician may insert a medical device, for example, a medical electrical lead, into the pericardial space. The physician will almost always need to direct the medical device within the pericardial space to a specific epicardial site where stable and effective medical therapy, according to the patient's needs, can be delivered from the device. Thus there is a need for delivery catheters formed to facilitate the delivery of medical devices to specific epicardial implant sites.